Methods for the treatment or prophylaxis of disease by inhibition of ornithine decarboxylase

ABSTRACT

Methods to prevent or treat conditions or diseases treatable by inhibition of ornithine decarboxylase are disclosed.

CROSS-REFERENCES TO RELATED APPLICATION

[0001] This is a divisional of U.S. patent application Ser. No. 09/919,692 filed on Jul. 31, 2001, the entire disclosure and contents of which are incorporated by reference.

BACKGROUND

[0002] 1. Field of the Invention

[0003] The present invention relates to methods of treatment or prevention of disease using salts of 2-difluoromethyl-2,5-diaminopentanoic acid (DFMO) with chitosan.

[0004] 2. Technical Field

[0005] This patent relates to the therapeutic use of salts of 2-difluoromethyl-2,5-diaminopentanoic acid (DFMO) with chitosan. DFMO, in vitro and in vivo, is an inhibitor of omithine decarboxylase, an enzyme that is involved in polyamine formation in organisms.

BACKGROUND OF THE INVENTION

[0006] In both eukaryotic and prokaryotic cells, the decarboxylation of omithine to putrescine, a reaction catalyzed by omithine decarboxylase (ODC), is the first step in the biosynthesis of the polyamines known as spermidine and spermine. The polyamines, which are found in animal tissues and microorganisms, are known to play an important role in cell growth and proliferation. The onset of cell growth and proliferation is associated with a marked increase in ODC activity and an increase in the levels of putrescine and the polyamines. Although the exact mechanism of the role of the polyamines in cell growth and proliferation is not known, it appears that the polyamines may facilitate macromolecular processes such as DNA, RNA, or protein synthesis. (Tabor H, Tabor C W, Cohn M S, Hafner E W. Streptomycin resistance produces an absolute requirement for polyamines for growth on an Escherichia coli strain unable to synthesize spermidine. J Bacteriolol 1981; 147: 702-4; Mamont P S, Bohelen, P, McCann P P, Bey P, Schuber R, Tardif C. Alpha-methyl omithine, a potent competitive inhibitor of omithine decarboxylase, blocks proliferation of rat hepatoma cells in culture. Proc Natl Acad Sci USA 1976; 73: 1626-30.)

[0007] The association between high levels of the polyamines and rapid proliferation was discovered more than a quarter of a century ago. (Bachrach U and Weinstein A. Effect of aliphatic polyamines on growth and macromolecular syntheses in bacteria. J. Gen. Microbiol., 60: 159-165 1970.) Subsequent studies showed that activation of the enzyme ODC was important for carcinogenesis and subsequent tumor development in animal and tumor models. (Weeks C E, Harmann A L, Nelson F R, Slaga T J. Alpha difluoromethylomithine, an irreversible inhibitor of omithine decarboxylase, inhibits tumor promoter-induced polyamine accumulation and carcinogenesis in mouse skin. Proc Natl Acad Sci USA 1982; 79:6028-32.)

[0008] It is currently known that increased intracellular polyamine concentrations are related to human neoplastic conditions. (Verma, A K Inhibition of tumor promotion by DL-alpha-difluoromethylomithine, specific irreversible inhibitor of ornithine decarboxylase. Basic Life Sci., 52:195-204, 1990). A further example of this relationship between high polyamine concentrations and neoplasms involves colonic polyps and cancers compared to surrounding normal colon mucosa. (Hixson, L J, Garewal, H S, McGee D., Sloan D, Fennerty, M B, Sampliner R E and Gerner E W Omithine decarboxylase and polyamines in colorectal neoplasia and adjacent mucosa. Cancer Epidemiol. Biomark. Prev. 2;369-374, 1993; Rozhin J, Wilson P S, Bull A W, and Nigro, N D. Omithine decarboxylase activity in the rat and human colon. Cancer Res. 44: 3226-3230, 1984.)

[0009] Other groups have reported that polyamine metabolism was necessary for carcinogenesis, especially in epithelial tissues. ODC inhibitors have been found to inhibit or suppress tumor formation in models of bladder, breast, colon and skin carcinogenesis. (Verma, A K Inhibition of tumor promotion by DL-alpha-difluoromethylomithine, specific irreversible inhibitor of omithine decarboxylase. Basic Life Sci., 52:195-204, 1990; Nigro N D, Bull A W and Boyd, M E. Inhibition of intestinal carcinogenesis in rats: effect of difluoromethylomithine for colon cancer prevention. J. Natl Cancer Inst. 77: 1309-1313, 1986; Thompson H J, and Ronan Am. Effect of DL-2-difluoromethylomrithine and endocrine manipulation on the induction of mammary carcinogenesis by 1-methyl-1-nitrosourea. Carcinogenesis (Lond.), 7: 20032006, 1986.)

[0010] It is thought, however, that the mechanism of cancer prevention by ODC inhibitors such as DFMO may involve more than just inhibition of cell proliferation. Animal studies show that DFMO may act at later stages in models of chemical carcinogenesis. These stages involve the transition of non-invasive tumors to invasive cancers. (Slaga, T J. Multistage skin carcinogenesis: a useful model for the study of the chemoprevention of cancer. Acta Pharmacol. Toxicol., 55 (Suppl. 2): 107-124, 1984.)

[0011] DFMO has been studied and continues to be studied as a cancer prevention agent, especially in skin, cervical and colon cancer. (Love R R, Carbone, P P Verma, A K, Gilmore D, Carey P, Tutsch K D. Pomplun M, and Wilding G. Randomized Phase I chemoprevention dose-seeking study of alpha-difluoromethylornithine. J. Natl. Cancer Inst., 85:732-736, 1993; Nishioka K, Melgarejo A B, Lyon R R and Mitchell M F. Polyamines as biomarkers of cervical intraepithelial neoplasia. J. Cell. Biochem., 23 (Suppl.): 87-95, 1995; Mitchell M F, Tortolero-Luna G, Lee J J, Hittelman W N, Lotan R, Wharton J T, Hong, W K and Nishioka, K. Phase I dose de-escalation trial of alpha-difluoromethylornithine in patients with grade 3 cervical intraepithelial neoplasia. Clin. Cancer Res., 4:303-310, 1998; Meyskens F I, Emerson S S, Pelot D, Meshkinpour H, Shassetz R, Einspahr J, Alberts D S, and Gerner, E W Dose de-escalation chemoprevention trial of alphadifluoromethylomithine in patients with colon polyps. J. Natl. Cancer Inst., 86:1122-1130, 1994.)

[0012] While high doses of DFMO in humans can cause some problems with hearing (reversible upon discontinuation of DFMO), at the doses used for chemoprevention of cancer (0.50 g/m2/day) such concerns have been found to be groundless. (Meyskens F L, Gerner E, Emerson S, Pelot D, Durbin T, Doyle K and Lagerber W. A randomized double-blind placebo controlled Phase IIb trial of difluoromethylornithine for colon cancer prevention. J. Natl. Cancer Inst., 90: 1212-1218, 1998).

[0013] DFMO has also been found useful in conditions unrelated to cancer. ODC inhibitors have been associated with control of hair growth. Studies in mice have suggested that the ODC gene is an important regulatory gene for the mouse hair follicle. (Soler A P, Gilliard G, Megosh L C, O'Brien T G. J Modulation of murine hair follicle function by alterations in omithine decarboxylase activity. Invest Dermatol 1996 May; 106(5):1108-13.) The FDA, to control facial hair growth in women, has recently approved DFMO. (Current DFMO salts, when used topically, cause burning, irritation and inflammation.) DFMO may have use in controlling male facial hair growth as well and may constitute a methodology to supplant or reduce the use of razors to remove facial hair in men.

[0014] Review of Prior Art

[0015] U.S. Pat. No. 4,330,559, May 18, 1982, Bey, et al. discloses the use of DFMO to treat benign prostatic hypertrophy. U.S. Pat. No. 4,399,151, Aug. 16, 1983, Sjoerdsma, et al. discloses the use of 2-(difluoromethyl)-2,5-diaminopentanoic acid (DFMO) for inhibiting the growth of protozoa. U.S. Pat. No. 4,405,530, Sep. 20, 1983, Gerhart, discloses the preparation of fluorinated amino-nitriles. These patents do not disclose the use of salts of DFMO with chitosan.

[0016] U.S. Pat. No. 4,413,141, Nov. 1, 1983 Bey, et al. discloses 2-(difluoromethyl)-2,5-diaminopentanoic acid (DFMO) and the methods for the preparation and use thereof U.S. Pat. No. 4,499,072, Feb. 12, 1985, Sunkara, et al. discloses the use of DFMO as an ODC inhibitor along with interferon in treating diseases. U.S. Pat. No. 4,720,489, Jan. 19, 1988, Shander, discloses the use of DFMO as an ornithine decarboxylase inhibitor to modify hair growth. These patents do not disclose the use of salts of DFMO with chitosan.

[0017] U.S. Pat. No. 5,648,394 Jul. 15, 1997, Boxall, et al. discloses the use of DFMO as a topical composition for inhibiting hair growth but does not teach the use salts of DFMO with chitosan. WO9814188, May 04, 1998, Love et al. teaches the use of preparations comprising a single enantiomer or defined ratio of enantiomers of alphadifluoromethylornithine (DFMO) for treating, preventing, controlling the growth of and/or reducing the risk of developing estrogen independent breast cancer or tumor and for administering DFMO alone or in combination with taxol. However, this patent does not teach the use of salts of DFMO with chitosan. U.S. Pat. No. 5,851,537, Dec. 22, 1998, Alberts et al. discloses the use of topical application of DFMO to prevent skin cancer but does not teach the salts of DFMO with chitosan. WO0069434, Nov. 23, 2000, Love discloses the use of Celecoxib, a COX-2 specific nonsteroidal antiinflammatory agent, in combination with DFMO for the prevention and/or treatment of cancers. However, this patent does not teach the salts of DFMO with chitosan. U.S. Pat. No. 6,166,079, Dec. 26, 2000, Follen et al. discloses the use of DFMO for the treatment or prevention of cervical intraepithelial neoplasia. U.S. Pat. No. 6,258,845, Jul. 10, 2001, Gerner, et al. discloses the use of DFMO and sulindac combination in cancer chemoprevention. These patents do not teach the use of salts of DFMO with chitosan.

[0018] Administration of agents that inhibit ornithine decarboxylase would have significant utility over a wide range of disorders or conditions associated with an increase polyamine metabolism. For example, in addition to the prevention and/or treatment of different types of cancer or precancer conditions, such agents would have utility in preventing and/or treating colon polyps, benign prostatic hypertrophy (BPH), or hirsutism. Such agents may also provide a means to decrease the need for daily shaving of facial hair in males.

[0019] Accordingly, there is a need in the art for methods related to the use of such ODC inhibition agents to prevent and/or treat conditions associated with increased polyamine metabolism. The present invention fulfills this need, and provides further related advantages.

SUMMARY OF THE INVENTION

[0020] Briefly stated, the present invention discloses methods for the use of salts of DFMO with chitosan. These salts of DFMO with chitosan have utility in treating or preventing a variety of conditions related to the aforementioned mechanisms of action of DFMO, namely ODC inhibition. Thus in one embodiment, a salt of DFMO with chitosan is administered to a warmblooded animal in need thereof to inhibit ODC. In yet a further embodiment, a salt of DFMO with chitosan is administered to a warm blooded animal to prevent and or treat the following conditions: aging of the skin, cancer, HIV, alopecia, solar keratosis, benign prostatic hypertrophy, prostate cancer, breast cancer, cervical cancer, and other such conditions in which polyamine metabolism requires modulation. Such a salt may be administered along with any other agent to enhance its therapeutic effectiveness. Other aspects of the present invention will become evident upon reference to the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

[0021] As mentioned above, this invention is generally directed to therapeutic uses of salts of DFMO with chitosan. Such salts of DFMO with chitosan, when administered to a warm-blooded animal in need thereof, have utility in the prevention or treatment of conditions enumerated above in warm-blooded animals, including humans.

[0022] The term “treat” or “treatment” means that the symptoms associated with one or more conditions mentioned above are alleviated or reduced in severity or frequency and the term “prevent” means that subsequent occurrences of such symptoms are avoided or that the frequency between such occurrences is prolonged.

[0023] It has now surprisingly been found that salts of DFMO with chitosan have good characteristics that are such as to render them particularly suitable both for use in pharmaceutical formulations and for preparative applications.

[0024] The example illustrates the complete absence of the well known irritation side effects of DFMO when a cream containing 20% salt of DFMO with chitosan is applied topically to the forearm of healthy volunteers.

[0025] This example is given to illustrate the present invention, but not by way of limitation. Accordingly, the scope of this invention should be determined not by the embodiments illustrated, but rather by the appended claims and their legal equivalents.

EXAMPLE 1

[0026] A cream containing 20% salt of DFMO with chitosan was applied to the forearm of 10 healthy individuals twice daily for a two-week period in an outpatient clinic. No patients complained of burning, irritation, scaling or redness after the cream. Patients returned to the clinic after having used the cream for two weeks for a visual inspection of the forearm area. The examining physician noted no redness, irritation or scaling in the area where the cream had been applied. 

I claim:
 1. A method for the treatment of a disease or a condition which is treatable by inhibition of ornithine decarboxylase, which comprises administration of a therapeutically active or nithine decarboxylase-inhibiting amount of a salt of 2-difluoromethyl-2,5-diaminopentanoic acid with chitosan.
 2. A method for the prevention of a disease or a condition which is preventable by inhibition of omithine decarboxylase, which comprises administration of a therapeutically active omithine decarboxylase-inhibiting amount of a salt of 2-difluoromethyl-2,5-diaminopentanoic acid with chitosan.
 3. The method as defined by claim 1, wherein a salt of 2-difluoromethyl-2,5-diaminopentanoic acid with chitosan is administered to treat a disease or condition selected from the group consisting of cancer, benign prostatic hypertrophy, protozoal in fections, actinic keratosis, and hirsutism.
 4. The method as defined by claim 2, wherein a salt of 2-difluoromethyl-2,5-diaminopentanoic acid with chitosan is administered to prevent a condition or disease selected from the group consisting of cancer, benign prostatic hypertrophy, HIV, prozoal infections, actinic keratosis, and hirsutism.
 5. A method wherein a salt of 2-difluoromethyl-2,5-diaminopentanoic acid with chitosan is administered topically to prevent hair growth. 